Based on a review of recent developments in Sweden and Finland, this chapter analyzes the roles of public organizations in the governance of a transition to Mobility-as-a-Service (MaaS). In particular, we draw on insights from transition frameworks to explore what these two pioneering cases can teach us about how the public sector can both enable the development of MaaS and steer the development trajectory toward diffusion of MaaS offerings that contribute to transport policy goals. We propose three main points. Firstly, public sector organizations at national, regional, and local levels have key roles to play in potential transitions to MaaS, regardless of their intended operative roles in the emerging MaaS ecosystem. Secondly, a central task for public sector organizations is to align operational and tactical MaaS governance activities with both an overarching MaaS strategy and with other relevant strategies, such as transport infrastructures investments, programs for economic and industrial growth, city plans, and parking norms. Thirdly, new models and tools for public–private collaboration are needed in order to effectively govern the development and diffusion of sustainable MaaS.